Move wrapPassthroughInternal out of headers.

Move implementation of wrapPassthroughInternal into
sources. Still provide a templated version for
convenient use (which should be optimized out
when not used).

This function:
- isn't template specific
- duplication takes up space on device/in-memory

Test: hidl's run_all_device_tests.sh
Bug: 33754152
Change-Id: I9e949f953732d843053ac5d6655700d48eda3190
diff --git a/transport/Android.bp b/transport/Android.bp
index dbbbdaf..23f6904 100644
--- a/transport/Android.bp
+++ b/transport/Android.bp
@@ -70,6 +70,7 @@
 
     srcs: [
         "HidlBinderSupport.cpp",
+        "HidlPassthroughSupport.cpp",
         "HidlTransportSupport.cpp",
         "HidlTransportUtils.cpp",
         "ServiceManagement.cpp",